Four-way valve and ice maker using such a four-way valve

ABSTRACT

The present invention relates to a four-way valve and an ice maker using such a four-way valve. A main valve of the four-way valve comprises a valve body and a slide seat formed integrally with the valve body. A valve core of the four-way valve may move between a first position and a second position. The valve core includes a sliding block slidable on the slide seat, wherein a recess is form on the sliding contact surface of the sliding block facing to the slide seat. A first port is formed on the valve body, and a second port, a third port, and a fourth port in the sliding direction of the sliding block are formed on the valve body. A radially inwards extending flange is provided in at least one of said second, third, fourth ports at the position proximal the slide seat, ensuring that, when the sliding block is located at any position between the first position and the second position, the recess enables at most two adjacent ports of said ports communicating each other, thereby avoiding the second, third, and fourth ports simultaneously communicating one another, thus preventing high pressure refrigerant from leaking into low pressure side.

FIELD OF THE INVENTION

The present invention relates generally to four-way valves for refrigerant circulating systems, particularly to a main valve of such a four-way valve. The present invention also relates to an ice marker using such a four-way valve.

BACKGROUND OF THE INVENTION

Conventional four-way valves can be broadly used in refrigerant circulating systems, such as refrigeration system. FIG. 9 a shows the prior art of the main valve in the four-way valve for refrigerant circulating systems. In the main valve, a 15 sliding block 103 a slides between a first position and a second position on a slide seat 25 a, when in the first position, the sliding block 103 a slides to left side establishing the communicating between a first port 93 and a fourth port 97, as well as a third port 96 and a second port 95; when in the second position, the sliding block 103 a slides to right side, establishing the communicating between a first port 93 and a second port 95, as well as a third port 96 and a fourth port 97.

However, if relatively lower refrigerating capacity is required by the refrigeration system, a small amount of refrigerant need to be charged into the refrigeration system with such a four-way valve, therefore, lower pressure is exerted onto a piston element 26 by refrigerant. This causes the sliding block 103 a slide slowly on the slide seat 25 a, thus, during moving between these two positions, the sliding block 103 a may be in such a position, where the second port 95, the third port 96, and the fourth port 97 communicate with one another, as shown in FIG. 9 a In such a case, because the pipeline connected to some of these ports are in high pressure, and the pipeline connected to other of these ports are in low pressure, high pressure and low pressure refrigerant in these pipeline communicate with each other, and the compressed, high pressure refrigerant leak into the low pressure pipeline, occurring the so-called “short-circuited”. This causes the sliding block 103 a stay the position as shown in FIG. 9 a, resulting in the refrigeration system operating abnormally.

If refrigerating capacity of an ice maker is relatively lower, such an ice maker can not use the four-way valve to control the refrigerant flow. As shown in FIG. 2 a and 2 b, conventional ice makers often use two solenoid valve to perform controlling, instead of the four-way valve. Due to employing more components and piping, such as solenoid valve W1, W2, and reservoir O, etc, the reliability and the utilization of refrigeration systems of such a conventional ice makers are reduced. Further, after ice making process, the ice maker need to switch from refrigerating mode to heating code, in order to result in the ice drop down from the ice-making member (i.e evaporator T), therefore, if the more the components and the piping, the more power loss and flow loss generated by the refrigerant switching between high pressure side and low pressure side during the switching process, further to lower the efficiency of the refrigeration system.

SUMMARY OF THE INVENTION

In order to eliminate or alleviate the problems and deficiencies in the prior art, the present invention provides an improved four-way valve and an ice maker using such a four-way valve. The four-way valve comprises: a main valve for determining refrigerant flow paths, a pilot valve for operating the main valve, and an electromagnetic coil for controlling the pilot valve. The main valve including: a valve chamber formed by a valve body; a slide seat formed integrally with the valve body; a valve core movable between a first position and a second position within the valve body, the valve core including a sliding block slidable on the slide seat, wherein a recess is formed on the sliding contact surface of the sliding block facing to the slide seat; and a first port formed on the slide seat, and a second port, a third port, and a fourth port formed on the valve body in the sliding direction of the sliding block. In the four-way valve, in the first position, the first port and the fourth port in communication with each other via a main valve chamber, and the second port and the third port in communication with each other via the recess; in the second position, the first port and the second port in communication with each other via the main valve chamber, and the third port and the fourth port in communication with each other via the recess. At least one of said second, third, fourth ports is provided with a radially inwards extending protrusion at the position proximal the slide seat, the protrusion is configured in such a way that, when the sliding block is located at any position between the first position and the second position, the recess enables at most two adjacent ports of said ports communicating each other. Thus, the second, third, and fourth ports can not be simultaneously communicated one another, thereby preventing high pressure refrigerant from leaking into low pressure side, avoiding the malfunction of the refrigerant circulating system, while improving the efficiency and the reliability of the system.

BRIEF DESCRIPTION OF THE DRAWINGS

A preferred embodiment and other aspects of the present invention will be best understood with reference to a detailed description of specific embodiments of the invention, which follows, when read in conjunction with the accompanying drawings, in which:

FIG. 1 illustrates a conventional solenoid valve,

FIG. 2 a and 2 b illustrate a refrigerant circulating system using the conventional solenoid valves, showing a refrigeration mode and a heating mode respectively;

FIG. 3 a and 3 b illustrate the four-way valve according to the present invention, showing a de-energized condition and an energized condition of an electromagnetic coil respectively,

FIG. 4 a and 4 b illustrate the refrigerant circulating system using the four-way valve according to the present invention, the systems shown are in the refrigeration mode and the heating mode respectively;

FIG. 5 illustrates the main parts of the ice maker using the four-way valve according to the present invention;

FIG. 6 illustrates the pilot valve of the four-way valve,

FIG. 7 a and 7 b illustrate the main valve of the four-way valve, and FIG. 7 c is a side view thereof,

FIG. 8 is a bottom view of the sliding block of the four-way valve,

FIG. 9 a illustrates a prior art main valve of a conventional four-way valve,

FIG. 9 b illustrates the main valve of the four-way valve according to the present invention,

FIG. 10 is a perspective of the ice maker according to the present invention;

FIG. 11 illustrates the main parts of the ice maker;

FIG. 12 illustrates an evaporator of the ice maker according to the present invention;

FIG. 13 illustrates a water storage box and an ice shovelling plate of the ice maker according to the present invention;

FIG. 14 illustrates a motor coupled to an inner casing;

FIG. 15 illustrates a photoelectric detecting device for the ice maker according to the present invention; and

FIG. 16 illustrates the water storage box rotating between two positions

Which the invention is susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in drawings and will be described in detail herein. However, it should be understood that invention is not intended to be limited to the particular forms disclosed. Rather, the invention is to cover all modification, equivalents and alternatives falling within the scope of the invention as defined by the appended claims.

DETAILED DESCRIPTION OF THE INVENTION

As shown in FIG. 3 a, 3 b, 7 a, and 7 b, a four-way valve M according to the present invention includes a pilot valve X, a main valve Y, and an electromagnetic coil Z. The main valve Y has a valve body 20 and a valve chamber formed by the valve body 20 In the valve chamber, a slide seat 25 is formed integrally with the valve body 20. A sliding block 103 can slide reciprocally on the slide seat 25, wherein a recess 30 is provided on the sliding contact surface 31 of the sliding block 103 facing the valve seat 25.

Two piston elements 26, 26 are respectively connected to the sliding block 103 on both sides of the sliding block 103. These two piston elements 26, 26 are closely fit within the valve chamber to match with the wall of the valve chamber, and can move reciprocally in the valve chamber, integrally with the sliding block 103, i.e. movable between the first position at left end of the valve body 20 and the second position at right end of the valve body 20. These two piston elements 26 divide the valve chamber into three sections, i.e. a first valve chamber 94 defined by the left-side piston element and the valve body, a main valve chamber 120 defined by these two piston elements and the valve body, and a second valve chamber 98 defined by the right-side piston element and the valve body.

A first port 93 is formed on the valve body 20, and a second port 95, a third port 96, and a fourth port 97 are formed on the valve seat 25. These ports may be connected to a refrigerant circulating system via piping. Four capillaries 90, 91, 99, 100 correct the pilot valve X with the main valve Y, so as to control the main valve Y by means of the pilot valve X.

Operation of the four-way valve M will be described as follow. As shown in FIG. 3 a and 7 a, when the electromagnetic coil Z is in de-energized condition, a valve core 101 of the pilot valve X is moved to the left-side of the drawings by a spring 102. In the refrigerant circulating system, high pressure refrigerant flows 15 through the first port 93 into the main valve Y, and flows serially through the capillary 90, the pilot valve X, and the capillary 100 into the second valve chamber 98 of the main valve Y The pressure of the high pressure refrigerant in the second valve chamber 98 applies onto the right-side piston element, causing the valve core including two piston elements 26 and the sliding block 103 to move integrally to the first position at the left end of the valve body Refrigerant in the first valve chamber 94 flows serially through the capillary 91, the pilot valve X, and capillary 99 to the third port 96. When in the first position, the first port 93 communicates with the fourth port 97 via the main valve chamber 120; the second port 95 communicates with the third port 96 via a recess 30 of the sliding block 103. The flow path of refrigerant fluid in the four-way valve M at this moment is shown in FIG. 3 a As shown in FIG. 3 b and 7 b, when the electromagnetic coil Z is in energized condition, a valve core 101 of the pilot valve X compresses the spring 102 by means of electromagnetic force generated by the electromagnetic coil Z, to move the right-side of the drawings. In the refrigerant circulating system, high pressure refrigerant flows through the first port 93 into the main valve Y, and flows serially through the capillary 90, the pilot valve X, and the capillary 91 into the first valve chamber 94 of the main valve Y. The pressure of the high pressure refrigerant in the first valve chamber 94 applies onto the left-side piston element, causing the valve core including two piston elements 26 and the sliding block 103 to move integrally to the second position at the right end of the valve body. Refrigerant in the second valve chamber 98 flows serially through the capillary 100, the pilot valve X, and capillary 99 to the third port 96. When in the second position, the first port 93 communicates with the second port 95 via the main valve chamber 120; the fourth port 97 communicates with the third port 96 via a recess 30 of the sliding block 103. The flow path of refrigerant fluid in the four-way valve M at this moment is shown in FIG. 3 b.

As mentioned above, depending on that the electromagnetic coil Z of the four-way valve M in de-energized or energized condition, the valve core of the main valve Y and its sliding block may be in the first or second position, so that these four ports of the four-way valve M and their piping can be switchable between one flow configuration and the other flow configuration.

The refrigerant circulating system of the ice maker according to the present invention will be described as follow. As shown in FIG. 4 a, 4 b, 5, and 11, the refrigerant circulating system comprises a compressor R, a condenser S, an evaporator T, an expansion device (capillary tube) N, and the four-way valve M according to the present invention. The system is evacuated firstly, and then charged with a refrigerant fluid, such as R-134 a, etc.

If ice making is to be required, the refrigerant circulating system switches into a refrigeration mode, i.e. ice-making mode. As shown in FIG. 4 a, under the control of a control unit, e.g. a monolithic processor, the electromagnetic coil Z of the four-way valve M is in de-energized condition. As noted above, the valve core of the four-way valve M is located in the first position, thereby causing the first port 93 and the fourth port 97 in communication with each other; and the second port 95 and the third port 96 in communication with each other High pressure refrigerant gas is discharged from the discharge end U of the compressor R, and flows through pipeline 105 into the first port 93 of the four-way valve M, then flows towards the fourth port 97 through an aperture 108 on the piston bracket locating in the main valve chamber 120 of the main valve Y, and thereafter flows serially through pipeline 109, the condenser S, the capillary tube N, the evaporator T, the pipeline 107, the second port 95 and the third 96 of the main valve Y, and the pipeline 106, finally flows back to a low pressure suction end V of the compressor R, so as to complete the circulating loop. Low pressure refrigerant entering into the compressor R is compressed to high pressure refrigerant in the compressor R, and discharged out of a discharge end U, thereby repeating a new circulating. At this time, the first port 93 and the fourth port 97 serve as a high pressure refrigerant inlet and a high pressure refrigerant outlet of the four-way valve M respectively. The second port 95 and the third port 96 serve as a low pressure refrigerant inlet and a low pressure refrigerant outlet of the four-way valve M respectively. It is appreciated by those skilled in the art that, the entire refrigerant circulating system may operate in a conventional vapor compression mode. In the ice-making mode, the refrigerant fluid dissipates heat on a heat exchange surface of the condenser S, and absorbs heat on a heat exchange surface of the evaporator T, as result that water in the vicinity of the heat exchange surface of the evaporator T freezes.

When the ice on the heat exchange surface of the evaporator T build up to a predetermined degree, the refrigerant circulating system is switched into heating mode, i.e. ice droping-off mode. As shown in FIG. 4 b, under the control of a control unit, e.g. a monolithic processor, the electromagnetic coil Z of the four-way valve M is in energized condition. As noted above, the valve core of the four-way valve M is located in the second position, thereby causing the first port 93 and the second port 95 in communication with each other, and the fourth port 97 and the third port 96 in communication with each other. High pressure refrigerant gas is discharged from the discharge end U of the compressor R, and flows through the pipeline 105 into the first port 93 of the four-way valve M, then flows towards the second port 95 through an aperture 108 on the piston bracket locating in the main valve chamber 120 of the main valve Y, and thereafter flows serially through pipeline 107, the evaporator T, the capillary tube N, the condenser S, the pipeline 109, the fourth port 97 and the third 96 of the main valve Y, and the pipeline 106, finally flows back to a low pressure suction end V of the compressor R, so as to complete the circulating loop. Low pressure refrigerant entering into the compressor R is compressed to high pressure refrigerant in the compressor R, and discharged out of a discharge end U, thereby repeating a new circulating. At this time, the first port 93 and the second port 95 serve as a high pressure refrigerant inlet and a high pressure refrigerant outlet of the four-way valve M respectively. The fourth port 97 and the third port 96 serve as a low pressure refrigerant inlet and a low pressure refrigerant outlet of the four-way valve M respectively. It is appreciated by those skilled in the art that, the entire refrigerant circulating system may operate in a conventional vapor compression mode. In the ice dropping-off mode, the refrigerant fluid dissipates heat on the heat exchange surface of the evaporator T, and absorbs heat on the heat exchange surface of the condenser S, as result that the ice freezing on the heat exchange surface of the evaporator T melts.

The refrigerant circulating system is switchable between the ice-making mode and the ice dropping-off mode by means of switching on or off the electric power supplied to the electromagnetic coil Z of the four-way valve M. In one preferred embodiment, the control unit includes the monolithic processor. Of course, it is appreciated by those skilled in the art that, other type control devices can also be used to achieve the above-mentioned operation. In the preferred embodiment, an ice-making period is set to for example 12, 15, or 18 minutes; an ice dropping-off period is set to for example 1.5 minutes. Of course, the ice-making and dropping-off period are set according to other factors, such as ambient temperature and water temperature.

In order to avoid the second port 95, the third port 96, and the fourth port 97 simultaneously communicating one another during the sliding block 103 moves between the first position and the second position, at least one of these ports at the position proximal the slide seat 25 is provided with a radially inwards protruding flange 121. The flange is configured in such a way that when the sliding block 103 is located at any position between the first position and the second position, the recess 30 which is formed on the sliding contact surface 31 of the sliding block 103 facing to the slide seat 25 enables at most two adjacent ports of the second port 95, the third port 96, and the fourth port 97 communicating each other, thereby avoiding occurring said simultaneous communicating one another, thus preventing high pressure refrigerant from leaking into low pressure side. Preferably, each of the second port 95, the third port 96, and the fourth port 97 at the position proximal the slide seat 25 is provided with a radially inwards protruding flange 121. As shown in FIG. 9 b, even when the sliding block 103 is located at central position of the sliding seat 25, these three ports are not simultaneously communicating one another, thereby preventing high pressure refrigerant from leaking into low pressure side, thus avoiding decreasing of refrigerating efficiency.

In one preferable embodiment of the invention, the second port 95, the third port 96, and the fourth port 97 are circular ports with same radius, and are in equally spaced manner longitudinally arranged in a row on the slide seat 25. As mentioned above, under the control of the pilot valve X, the sliding block 103 together with the valve core slides in the longitudinal direction to the first position or the second position on the slide seat 25 In such a case, the recess 30 which is formed on the sliding contact surface 31 of the sliding block 103 facing to the slide seat 25 is dimensioned in the longitudinal direction, such that the longitudinal dimension of the recess 30 is not more than the sum of two times of the port radius and the distance between the centers of these two adjacent ports, i.e., S≦Dt+2r, wherein, S is the longitudinal dimension of the recess, d is the distance the centers of two ports, and r is port radius, furthermore, the longitudinal dimension of the recess is not more than the result of twice the distance between the centers of the two adjacent ports minus twice the port radius, i.e S≦2D-2r, wherein, S is a length of the recess D is the distance the centers of two ports, and r is port radius. At this point, even though the at least one of the ports at the position proximal the slide seat 25 is not provided with the flange 121, the recess 3 is dimensioned as such to avoid these ports 95, 96, and 97 simultaneously communicating one another. Of course, it is preferable that the flange is provided and the recess is dimensioned as such. It is appreciated by those skilled in the art that, the flange may be replaced with other equivalent forms, such as a stepped portion, a boss, a protrusion, and tab, etc.

In use, for a refrigerant circulating system employing R-134 a refrigerant, the high pressure of the discharge end U of the compressor R is up to 1.5 MPa, and the low pressure of the suction end V of the compressor R is as low as 0.1 MPa. Although pressure difference of these two pressure is very high, the experimental results show that, the amount of leakage through the gap between the sliding contact surface 31 of the sliding block 103 and the slide seat 25 is not more than 50 ml/min. This leakage amount is very low, and may be considered to be “no leakage”.

In another preferred embodiment, as shown in FIG. 7 a and 7 b, between the sliding block 103 and the piston bracket 23 is provided a spring leaf 24, whose elastic force causes the sliding block 103 to press against the slide seat 25, thereby decreasing the gap therebetween, further preventing the leakage from high pressure side to low pressure side.

In yet another preferred embodiment, the slide seat 25 and the sliding contact surface 31 of the sliding block 103 facing to the slide seat 25 is manufactured by finish machining, thereby having high precision This causes the sliding block 103 and the slide seat 25 to be more closely abutted against each other, thereby further decrease the gap therebetween, preventing the leakage from high pressure side to low pressure side.

In another aspect of the invention, there is provided an ice maker according to the present invention. As described above, the refrigerant circulating system of the ice maker is shown in FIG. 4 a and 4 b The four-way valve according to the invention is used to switch the refrigerant circulating system between the refrigeration mode and the heating mode. Due to the use of the four-way valve according to the invention, the ice maker using such a four-way valve may quickly switch between the refrigeration mode and the heating mode, prevent the high pressure refrigerant fluid from leaking into the low pressure pipelines, thereby eliminating the problem in the prior art, thus, avoiding the malfunction of the refrigerant circulating system, on the other hand, decrease the number of the components used, thereby improve efficiency and reliability of the system. The experimental results show that, at same conditions, the ice making amount of the ice maker with the four-way valve according to the invention improve by 50% compared with that of the conventional ice maker with solenoid valves.

Other aspects of the ice maker according to the invention will be described as follow.

As shown in FIG. 11, the four-way valve M and the refrigerant circulating system are mounted within the housing of the ice maker. Pipelines are connected to the ports 93, 95, 96, and 97 by means of brazing, and fixed in the housing of the ice 25 maker by a metal bracket G. The metal bracket G at its upper end fastens the main valve Y of the four-way valve M, and at its lower end is fixed onto the base plate H of the ice maker, ensuring that the four-way valve M be fixed within the housing of the ice maker.

As shown in FIG. 11, 12, and 13, an evaporator T, a water storage box 51, and an ice shovelling plate 53 form the ice making components. FIG. 12 shows the evaporator T, comprising a U-shaped pipe 46, a plurality of icing tubes 48, a holding frame 47, and an inlet/outlet pipe 49. The plurality of the icing tubes 48 at their lower ends are sealed, and at their upper ends connected to the U-shaped pipe 46 by means of brazing. At each connection, the U-shaped pipe 46 is provided with holes (not shown), so as to the U-shaped pipe 46 internally communicating with respective icing tubes 48 The water storage box 51 is charged with water by a pumping unit (not shown), thereby make the icing tube 48 underneath water level.

As shown in FIG. 14 and 15, the water storage box 51 is positioned within the inner casing 1. The inner casing 1 is fixed onto the base plate H. A shaft 54 extends from one side of the water storage box 51 to exterior and through the inner casing 1, and the shaft 54 is formed integrally with the water storage box 51. A detector fixture 37 is secured on one side of the inner casing 1. A shading piece 36 is provided on the shaft extending outwards from the water storage box 51. Photoelectric detectors 35,38 are provided on both ends of the detector fixture 37. The photoelectric detecting device is formed by the shading piece 36, the detector fixture 37, and the photoelectric detectors 35,38. Furthermore, a motor J is fixed on the other side of the inner casing 1. The shaft of the motor J is fit with an adapter 55 integrally provided on the other side of the water storage box 51, in order that the motor J drives the water storage box 51 to rotate

In ice making mode, the water storage box 51 is positioned as dash and dot line K shown in FIG. 16 At this time, because there is lower temperature refrigerant in the icing tube 48, water surrounding the icing tube 48 is frozen to form ice columns. When ice columns build up to predetermined degree, the control unit of the ice maker supplies a signal, so as to instruct the motor J to drive the water storage box 51 with the shading piece 36 together to rotate counterclockwise around the shaft 54 and the adapter 55 When the water storage box 51 rotates to the position shown as dashed line of FIG. 16, the shading piece 36 is detected by the photoelectric detector 38, at this time, the control unit supplies a signal, so as to cause the motor J to stop, and energize the electromagnetic coil Z of the four-way valve M, thereby switch to the ice droping-off mode. In the ice droping-off mode, because there is higher temperature refrigerant in the icing tube 48, ice surrounding the icing tube 48 melt, so that hollow tube shape of ice blocks drop off from the icing tube 48. When ice dropping off is finished, the control unit supplies a signal, so as to instruct the motor J to drive the water storage box 51 with the shading piece 36 together to rotate clockwise around the shaft 54 and the adapter 55. When the water storage box 51 rotates to the position shown as dash and dot line K of FIG. 16, the shading piece 36 is detected by the photoelectric detector 35, at this time, the control unit supplies a signal, so as to cause the motor J to stop, and de-energize the electromagnetic coil Z of the four-way valve M, thereby switch to the ice making mode again. The pumping unit charges the water storage box 51 with water again, in order to start the next ice making process. During the motor J drives the water storage box 51 to rotate clockwise, the ice shovelling plate 53 hinged with the water storage box 51 shovels the ice blocks in the direction as arrow shown in FIG. 16 into an ice storage box B

The ice maker according the invention may conveniently and quickly make the edible ice or ice blocks for cooling foods. The ice maker may be for domestic or commercial purposes, such as pubs and restaurants, etc.

Which the invention has been described with reference to the preferred embodiments, obvious modifications and alternations are possible by those skilled in the related art. Therefore, it is intended that the invention include all such modifications and alternations to the full extent that they come within the scope of the following claims or the equivalents thereof. 

1. A four-way valve (M) for a refrigerant circulating system, comprising: a main valve (Y) for determining refrigerant flow paths, a pilot valve (X) for operating the main valve (Y), and an electromagnetic coil (Z) for controlling the pilot valve (X), the main valve (Y) including: a valve chamber formed by a valve body (20); a slide seat (25) formed integrally with the valve body (20); a valve core movable between a first position and a second position within the valve body (20), the valve core including a sliding block (103) slidable on the slide seat (25), wherein a recess (30) is form on the sliding contact surface (31) of the sliding block (103) facing to the slide seat (25); and a first port (93) formed on the valve body (20), and a second port (95), a third port (96), and a fourth port (97) formed on the slide seat (25) in the sliding direction of the sliding block (103), in the first position, the first port (93) and the fourth port (97) in communication with each other via a main valve chamber (120), and the second port (95) and the third port (96) in communication with each other via the recess (30); in the second position, the first port (93) and the second port (95) in communication with each other via the main valve chamber (120), and the third port (96) and the fourth port (97) in communication with each other via the recess (30), said four-way valve (M) characterized in that, at least one of said second, third, fourth ports (95, 96, 97) is provided with a radial inwards extending protrusion at the position proximal the slide seat (25), the protrusion is configured in such a way that, when the sliding block (103) is located at any position between the first position and the second position, the recess (30) enables at most two adjacent ports of said ports (95, 96, 97) communicating each other.
 2. A four-way valve of claim 1, characterized in that, each of said second, third, fourth ports (95, 96, 97) is provided with the protrusion, and said protrusion comprises at least one flange (121).
 3. A four-way valve of claim 1, characterized in that, the second port (95), the third port (96), and the fourth port (97) are circular ports with same radius, and are in equally spaced manner longitudinally arranged in a row on the slide seat (25), the recess (30) which is formed on the sliding contact surface (31) of the sliding block (103) facing to the slide seat (25) is dimensioned in the longitudinal direction, such that the longitudinal dimension of the recess (30) is equal or smaller than the sum of two times of the port radius and the distance between the centers of the two adjacent ports, i.e., S≦D+2r, wherein, S is the longitudinal dimension of the recess, d is the distance the centers of two adjacent ports, and r is port radius.
 4. A four-way valve of claim 3, characterized in that, the longitudinal dimension of the recess (30) is equal or smaller than the result of twice the distance between the centers of the two adjacent ports minus twice the port radius, i.e., S≦2D-2r, wherein, S is a length of the recess, D is the distance the centers of two adjacent ports, and r is port radius.
 5. A four-way valve of claim 1, characterized in that, a spring leaf (24) is provided between the sliding block (103) and the piston bracket (23), an elastic force of the spring leaf (24) causes the sliding block (103) to press against the slide seat (25), thereby decreasing the gap therebetween, further preventing the leakage from high pressure side to low pressure side.
 6. A four-way valve of claim 5, characterized in that, during operating of the four-way valve (M), the amount of leakage through the gap between the sliding contact surface (31) of the sliding block (103) and the slide seat (25) is not more than 50 ml/mm.
 7. An ice maker having a refrigerant circulating system, the ice maker comprising: a compressor (R) for compressing refrigerant; a condenser (S) for condensing the compressed refrigerant and dissipating heat 30 to exterior; a capillary tube (N); and an evaporator (T) in which the refrigerant evaporates and absorbs heat, the evaporator serving as an ice making member of the ice maker, said ice maker characterized in that, the refrigerant circulating system including a four-way valve (M) described as 1, for switching between the ice making mode the ice-dropping mode.
 8. An ice maker of claim 7, characterized in that, the evaporator (T) comprising a U-shaped pipe (46), a plurality of icing tubes (48), a holding frame (47), an inlet pipe, and an outlet pipe, and the plurality of icing tubes (48) at their lower ends are sealed, and at their upper ends connected to the U-shaped pipe (46) by means of brazing, at each connection, the U-shaped pipe (46) internally communicating with respective icing tubes (48).
 9. An ice maker of claim 7, characterized in that, the ice maker including a water storage box (51), the plurality of icing tubes (48) being underneath the water level in the water storage box (51), and the ice maker further including a motor (J), wherein after an ice making process is finished, the motor (J) drives the water storage box (5 1) to rotate out of an initial position, and the ice maker is switched to an ice-dropping mode, so as to cause ice to drop off; when the ice-dropping process is finished, the motor (J) drives the water storage box (51) to rotate back to the initial position.
 10. An ice maker of claim 9, characterized in that, further including a photoelectric detecting device comprising a shading piece (36), a detector fixture (37), and photoelectric detectors (35, 38), wherein the shading piece (36) may rotate together with the water storage box (51) by means of the motor (J), and the photoelectric detectors (35, 38) may sense the rotating of the shading piece (36), thereby controlling the motor (J) by means of a control unit.
 11. An ice maker of claim 9, characterized in that, during the motor (J) drives the water storage box (51) to rotate back to the initial position, an ice shovelling plate (53) hinged with the water storage box (51) shovels the ice blocks dropped off into an ice storage box (B). 